DC593A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 593
EVALUATION CARD FOR THE LT1637 IN THE DFN PACKAGE
LT1637CDD
DESCRIPTION
Demonstration circuit 593 simplifies the evaluation of
the LT1637CDD op amp in the tiny, 3mm × 3mm, DFN
(Dual in-line, Flat, No-leads) chip-scale package. Electrical performance of this LT1637 is the same as previous
versions. This version is only a packaging enhancement.
An evaluation circuit can easily be built on this board
without handling the tiny DFN device. Pads are provided
for adding external components and holes are available
for jumpers, signal I/O and supply wires. Supply bypass
capacitors are already on the board. Alternatively adding
two 4-pin headers (0.1" spacing) converts the board to a
standard 8-pin DIP format for use with a socket on a
second circuit board.
The backside of this evaluation board is void of metal to
allow wiring into an existing system with the board resting on top of other components.
About the LT1637CDD
The LT1637 is an Over-The-Top, Micropower, Rail-to-Rail
Input and Output Op Amp
 Input Common Mode Range Extends 44V Above V–
Independent of V+
 190µA Supply Current, 25mA Output Current
 Reverse Battery Protected to 25V
 Drives 4700pF CLOAD with compensation
 Output Shutdown, ISUPPLY = 3µA
 Output Swings to Within 3mV of V– and 25mV of V+
 Total Supply Voltage Range: 2.7V to 44V
Table 1. Typical Performance Summary (Single 3V Supply, TA=25°C) Visit www.linear.com for complete data sheet.
PARAMETER
CONDITION
VALUE
Input Voltage Range
Min and Max
0V to 44V
Supply Current
190µA
Offset Voltage (Null pins provided)
100µV
Input Bias Current
20nA
Gain Bandwidth Product
1MHz
Slew Rate
0.35 V/µsec
Device Top Mark Identifier: LAAK
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 593
EVALUATION CARD FOR THE LT1637 IN THE DFN PACKAGE
QUICK START PROCEDURE
Build the evaluation circuit in one of two ways as shown in Figures 1 and 2.
VCC
GND
VEE
C1
C3
R2
EOUT
R4
C4
LA xx
R1
EIN
GND
R3
GND
C2
Figure 1. External Components Directly on the PCB (0.1•F Bypass Capacitors: AVX 1206C104KAT). Example connections shown may not
be correct for this device.
GROUND WIRE
FOR BYPASS CAPS
DEMONSTRATION
CIRCUIT
DFN
PACKAGE
8-PIN DIP
SOCKET
HEADER: MILL-MAX
3402-0-00-21-00-00-03-0
TEST
BOARD
Figure 2. Convert the Board to an 8-pin DIP Format
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 593
EVALUATION CARD FOR THE LT1637 IN THE DFN PACKAGE
PACKAGE AND CONNECTION DRAWING
R = 0.115
TYP
5
0.38 ± 0.10
8
0.58 ±0.05
3.35 ±0.05
1.65 ±0.05
2.25 ±0.05 (2 SIDES)
3.00 ±0.10
(4 SIDES)
PACKAGE
OUTLINE
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(DD8) DFN 0902
0.28 ± 0.05
0.75 ±0.05
0.200 REF
4
0.28 ± 0.05
1
0.50 BSC
0.50
BSC
2.38 ±0.05
(2 SIDES)
0.00 – 0.05
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. ALL DIMENSIONS ARE IN MILLIMETERS
3. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
4. EXPOSED PAD SHALL BE SOLDER PLATED
TOP VIEW
NULL 1
8
NULL
–IN 2
7
V+
+IN 3
6
OUT
–
5
SHDN
V
4
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
ASSEMBLY TIPS
Following are the recommended procedures for soldering surface mount packages to PC boards.
− Activation temperature 130°C to 150°C
 Reflow Soldering with Solder Paste
− Time above 183°C for 30 seconds
• Use of solder plated boards is recommended.
• Screen solder paste on board.
• Mount components on board.
• Infrared or forced hot air convection reflow is recommended for best performance. Parameters:
− Preheat peak temperature 125°C ± 15°C and 2°C
to 4°C per second rise
− Reflow begins at 183°C (63Sn/37Pb)
− Peak package body temperature 220°C to 245°C
− Dwell time at peak temperature 10 seconds max
− Cooling rate 2°C to 4°C per second
− Clean boards.
• For Vapor Phase Reflow, recommended parameter
ranges for:
− Heating rate: 4°C per second max
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 593
EVALUATION CARD FOR THE LT1637 IN THE DFN PACKAGE
− Preheat temperature: 45°C to 80°C
− Time above 200°C: 50 seconds to 90 seconds
− Peak package temperature: 212°C to 219°C
 Wave Soldering and Hand Soldering are not recommended.
REWORK GUIDELINES FOR DFN PACKAGES
Each package mounting site should be reworked one at a
time only, to ensure maximum quality and reliability.
Linear Technology has found the following rework procedure to be effective with DFN packages but by no
means excludes other methods more suited to specific
manufacturing needs.
 Reflow Temperature Profile
Each package site to be reworked should be individually heated. The reflow temperature profile can be established using a hot gas tool and a thermocouple
embedded in the solder joints of a sample setup unit
on the PCB.
 Preheating and Package Removal
A package rework tool with vacuum pickup similar to
the A.P.E. Flo-Master can be used. A bottom PCB
heater is required to provide preheating of the PCB to
approximately 110°C to 120°C. The rework nozzle
must be centered with respect to the package in order
to direct the hot gas flow over the top of the package
while limiting the temperature of the adjacent components to prevent solder reflow.
 Site Rework
With a combination on hot gas/vacuum desoldering
tool and solder wick ribbons (if necessary), remove
the package and any remaining solder residues. Use a
minimal amount of flux if it is required to remove solder residue. This will also assist in leaving a smooth,
flat surface for the reattachment of a replacement
unit. The site for the package should be thoroughly
cleaned with isopropyl alcohol (IPA) and dried with
clean dry air (CDA).
 Solder Paste Application
Solder paste may be screen printed on to the package
landing site and exposed heat sink pads. Stainless
steel stencils are recommended for solder paste application. The printed solder deposits should be 100
percent inspected for uniformity of size and shape.
Some applications may have severe space constraints
preventing screen printing to be accomplished on the
PCB. Therefore, solder paste can be directly applied to
the packages landing site and exposed heatsink pad.
The package is to be picked and placed using a vision
aided system similar to the A.P.E. Sniper SMD 7007
Rework System.
 Reflow Process
The replacement package, once it has been placed
onto the reworked PCB landing site, should be reflowed on the PCB using a hot gas tool on the top of
the package and a heater on the bottom of the PCB.
The reflow temperature should not exceed 240°C.
Note that liquidus temperature for 63/37 Sn/Pb solder
is 183°C. Make sure to limit adjacent components to
below the solder reflow temperature. The solder paste
manufacturer’s recommended reflow temperature
profile/specifications must be complied with to avoid
damage to the PCB and/or adjacent components. A
100 percent post rework visual inspection for good
joint wetting is recommended.
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